Resistor in your spark plug cap + resistor in your spark plugs = tiny spark

[Isaanbiker]

    A long story short, I finally figured out why my front spark plug always got dark. I bought the bike 14 months ago and it had NGK BPR 7 ES in it. I thought that I'd do a good deed and ordered Iridium BPR 7 EIX from a guy in the UK.

 

    Still the same problem, changed the coils to see if it's gone, but nope. Then I saw at night that one spark plug unloaded through the insulator on minus of the spark, where the insulator ends. The carbs needed an overhaul, so I ordered a kit and did that as well. But the problem didn't go away. 

 

    After some reading and having a great support of a Virago Facebook group with very knowledgeable guys, I found out that The BPR plugs have around 5 K Ohm resistor in it and another 5 K Ohm are in the plug caps. 

 

    I finally ordered the right plugs, NGK BP 7 ES and the problem is gone. I really worked almost every day, made the carbs richer and leaner, but I wasn't successful.

 

When I posted that in our Virago group it turned out that quite a few others had very similar issues. I'm aware that some bikes have 10 K Ohm, or more resistance, depending on the ignition system.

 

But for such bikes, either 5 K in the caps, or 5 K Ohm in the spark plugs. The photo shows the fake Iridium that misfired on minus. I thought it's worth to share this experience with guys who have older bikes. 

 

And please be careful when buying Iridium plugs on e-bay. It turned out that almost all sellers from the UK sell fake ones, even warning buyers of sellers of fake ones. 

 

   Money is a bitc_. Ride safe out there. 

 

         

 

 

   

[Kwasaki]

1 hour ago, Isaanbiker said:

NGK BP 7 ES

 Yep for sure NGK Copper Core Spark Plug BP7ES are velly good. ????

 

 

[papa al]

"Resistor in your spark plug cap + resistor in your spark plugs = tiny spark"

 

that's what she said

[Damrongsak]

1 hour ago, papa al said:

"Resistor in your spark plug cap + resistor in your spark plugs = tiny spark"

 

that's what she said

Diesel is the only way to go.  Direct injection and high pressure.

[thaiguzzi]

NGK red plug caps are R rated ie resistors, black NGK plug caps have no resistors.

R on the spark plug denotes a resistor plug.

You do not need both on the same motorcycle.

Modern bikes, and i mean 60's onwards that ran points & condensors, then electronic ignition, then EFI require an R somewhere in the system, mainly for radio, tv and electonics interference.

Prior to battery and coil systems, there was/is no need for an R in the system, ie magneto ignition etc.

My 80's Yamaha trials bikes which run CDI, coil, and flywheel mag run better with R plugs, than without, as spec'd by the service manual.

Or better put, plain plugs die quicker than R plugs in those bikes.

My Triumph runs no R plugs, and, er, no R plug caps........

 

[Isaanbiker]

6 hours ago, papa al said:

"Resistor in your spark plug cap + resistor in your spark plugs = tiny spark"

 

that's what she said

It wasn't about my tiny thingy this time.......????

[Isaanbiker]

2 hours ago, thaiguzzi said:

NGK red plug caps are R rated ie resistors, black NGK plug caps have no resistors.

R on the spark plug denotes a resistor plug.

You do not need both on the same motorcycle.

Modern bikes, and i mean 60's onwards that ran points & condensors, then electronic ignition, then EFI require an R somewhere in the system, mainly for radio, tv and electonics interference.

Prior to battery and coil systems, there was/is no need for an R in the system, ie magneto ignition etc.

My 80's Yamaha trials bikes which run CDI, coil, and flywheel mag run better with R plugs, than without, as spec'd by the service manual.

Or better put, plain plugs die quicker than R plugs in those bikes.

My Triumph runs no R plugs, and, er, no R plug caps........

 

Bike came with Denso caps and they do have 5.2 K Ohm resistance. 

As far as I now are the OEM caps from NGK for Viragoes also with resistors. 

 

There might be caps with and without resistors. Here's some NGK spark plug info

Spark Plugs NGK Info.pdf

[thaiguzzi]

13 minutes ago, Isaanbiker said:

Bike came with Denso caps and they do have 5.2 K Ohm resistance. 

As far as I now are the OEM caps from NGK for Viragoes also with resistors. 

 

There might be caps with and without resistors. Here's some NGK spark plug info

Spark Plugs NGK Info.pdf 2.06 MB · 0 downloads

Thanx, but i already have NGK worldwide catalogues and manuals here, for every 4 wheeler, jet ski, ag power tool and motorcycle ever invented.

And Champion.

And cross references.

Up to 2003.

I doubt they've changed too much in the last 12 years.

 

It is also why i don't take too much notice of the latest fads like Iridium plugs or Splitfire plugs....

 

 

I have a decent selection.... and yeah, that is an official dealer metal display case....

[papa al]

mylar ceiling?

[thaiguzzi]

57 minutes ago, papa al said:

mylar ceiling?

Stainless...

...polished shiny stainless....

[chickenslegs]

18 minutes ago, thaiguzzi said:

Stainless...

...polished shiny stainless....

Thought it looked better in the workshop than the bedroom?????

[Isaanbiker]

On 11/4/2019 at 6:52 AM, Damrongsak said:

Diesel is the only way to go.  Direct injection and high pressure.

Okay, will try to fit my 2.8 liter Mitsy L 200 Diesel engine into my bike. Perhaps tiny modifications with the frame and drive shaft only. 

[canthai55]

On 11/4/2019 at 6:52 AM, Damrongsak said:

Diesel is the only way to go.  Direct injection and high pressure.

If you have a truck - by that I mean GVW of over 20,000

For cars - <deleted>

 

[Isaanbiker]

On 11/4/2019 at 12:41 PM, Isaanbiker said:

Bike came with Denso caps and they do have 5.2 K Ohm resistance. 

As far as I now are the OEM caps from NGK for Viragoes also with resistors. 

 

There might be caps with and without resistors. Here's some NGK spark plug info

Spark Plugs NGK Info.pdf 2.06 MB · 1 download

How's the one coil for two plugs working? 

[ballpoint]

On 11/4/2019 at 8:00 PM, thaiguzzi said:

Stainless...

...polished shiny stainless....

I'm disappointed.  I thought you would have at least engine turned it.

[thaiguzzi]

20 minutes ago, ballpoint said:

I'm disappointed.  I thought you would have at least engine turned it.

Its how it came from the container company.

Both containers are ex NZ Lamb refrigeration jobbies.

That one is fibreglass internal walls with a polished stainless ceiling, the other one is the same, but with brushed finished stainless walls.

Possibly ezy-clean to wipe the blood off?

Both had grated floors before i had chipboard flooring put in.